What does normally open mean in a ladder logic contact?

• A. It closes when energized.
• B. It opens when energized.
• C. It is always closed.
• D. It is an output device.

Answer: (A)

Normally open means the contact does not conduct current by default. When the control input is energized, the contact closes and completes the circuit, allowing current to flow. In ladder logic this models a switch that only passes current when activated, such as a NO pushbutton used to start equipment. If it opened when energized, that would describe a normally closed contact, which is closed at rest and opens when energized. An output device would be something that produces a signal or actuation, not the switching element itself.